1. Field of the Invention
The present invention relates to a bearing lubricating system which may be utilized to efficiently lubricate a thrust bearing that is incorporated in an automatic transmission of an automobile, for example.
2. Description of the Prior Art
A planetary gear device such as that shown in FIG. 6 is incorporated in an automatic transmission of an automobile, for example.
The illustrated planetary gear device is arranged such that a planetary gear 4 is supported through a roller bearing 12 on a planetary shaft 3 that is supported on the side of a supporting plate 2 secured to the outer peripheral surface of a shaft 1 and the planetary gear 4 is meshed with a sun gear 5 which is rotatable around the shaft 1 and a ring gear 7 which is secured to the inner peripheral surface of a ring carrier 6.
Between the ring carrier 6 and the supporting plate 2 are provided a thrust bearing 8 comprising a plurality of rollers 14 retained by a retainer 13 and a pair of races 15 and 16 which are disposed so as to sandwich the rollers 14 therebetween, thereby enabling relative rotation of the ring carrier 6 and the supporting plate 2.
The shaft 1 has a lubricating oil supply passage 9 in the center thereof, and an outlet port 10 is provided in an intermediate portion of the shaft 1 which faces the inner peripheral edge of the thrust bearing 8. The planetary shaft 3 has an oil passage 11 provided therein which opens to one end surface of the planetary shaft 3 and to the outer peripheral surface of the intermediate portion thereof.
The lubricating oil supply passage 9 is supplied with a lubricating oil by the action of a mechanism (not shown), so that the lubricating oil spouts from the outlet port 10 toward the inner peripheral edge of the thrust bearing 8, thereby lubricating the bearing 8. After lubricating the thrust bearing 8, the oil passes through the oil passage 11 provided inside the planetary shaft 3 and then lubricates the roller bearing 12 that is provided between the outer peripheral surface of the planetary shaft 3 and the inner peripheral surface of the planetary gear 4.
Incidentally, Japanese Utility Model Public Disclosure (Kokai) No. 63-36207 (1988) discloses oil guide structures such as those shown in FIGS. 7 and 8, which are designed to efficiently guide the lubricating oil having passed through the thrust bearing 8 into the oil passage 11 provided inside the planetary shaft 3.
The oil guide structure that is shown in FIG. 7 is arranged to guide the lubricating oil from the thrust bearing 8 toward the oil passage 11 by means of a ring-shaped weir plate 17 which is provided between the outer peripheral edge of the thrust bearing 8 and the opening of the oil passage 11 and an oil guide plate 18 which is provided at the opening of the oil passage 11. The oil guide structure shown in FIG. 8 is arranged to guide the lubricating oil from the thrust bearing 8 toward the oil passage 11 by means of a raised portion 19 that is formed on the ring carrier 6 and the oil guide plate 18.
However, the conventional bearing lubricating systems arranged as described above suffer from the following problems:
The operation of securing the weir plate 17 to the side surface of the ring carrier 6 or forming the raised portion 19 thereon is complicated and troublesome, which causes a rise in the production cost of a transmission, for example, which incorporates the lubricating system.
If the assembly operator forgets to incorporate the weir plate 17 or the oil guide plate 18, the lubricating oil having passed through the thrust bearing 8 cannot be efficiently guided into the oil passage 11, which is likely to result in a failure in lubrication of the roller bearing 12 supporting the planetary gear 4.
FIGS. 9 and 10 show other conventional structures for guiding the lubricating oil having passed through the thrust bearing 8 into the oil passage 11.
The structure shown in FIG. 9 is arranged to guide the lubricating oil having passed through the thrust bearing 8 into the oil passage 11 inside the planetary shaft 3 through a passage 21 which is formed in the inner peripheral portion of a stopper plate 20 that is provided to prevent the planetary gear 4 from coming off the planetary shaft 3. The oil guide structure shown in FIG. 10 is arranged to guide the lubricating oil having passed through the thrust bearing 8 into the oil passage 11 inside the planetary shaft 3 through a groove 22 which is formed in the end face of the sun gear 5 and the passage 21 that is formed in the inner peripheral portion of the stopper plate 20.
The prior art oil guide structures shown in FIGS. 9 and 10 also involve a complicated machining process which leads to a rise in the production cost. In the case of the structure shown in FIG. 10, the race 15 has no support at the portion thereof that faces the groove 22. There is therefore a fear that a part of the race 15 may be gradually deformed during use, resulting in the lifetime of the thrust bearing 8 being shortened.
Further, none of the prior arts are capable of efficiently guiding the lubricating oil spouting from the outlet port 10 toward the thrust bearing 8.